Fermenting Under Pressure

[wynnum1]

Looked at a couple of you tube videos for Fermentasaurus where they take the bottle off the base and replace and would think filling with water would be best way to eliminate oxygen when they replace to dry hop or collect more yeast.

 

[mtb]

I plan to dry hop in my fermentasauruses about ten points above FG. That oxygen ought to be consumed by the fermentation in progress.

 

[fungrel]

I have ordered a DO meter that is on its way,so soon as I get it I will be able to tell you, at the moment I just know there is some in the tap water. I did read the whole of the Low dissolved oxygen brewing techniques thread very interesting and some things I will be using myself, have been looking at the other sites on line as well. Lots of info here.
http://www.lowoxygenbrewing.com/uncategorized/list-of-brewing-references/

You have a spare 400+ to spend on a meter?

 

[wide eyed and legless]

 

[Dan Pratt]

I've dedicated a keg to dry hopping. Cut the dip tube shorter to allow for 100gm of hops. Pressure transfer to co2 flushed dry hop keg and every day flip it over to rouse the hops. Pressure transfer from hop keg to serving keg.

this frees up the FV and also allows the hops to get better extraction and very low oxygen ingress.

 

[Gelding]

I know there is a popular belief that yeast can suffer detrimental effects under pressure. But follow me for a minute here.
Lets take a small/medium craft brewer like Wayward for instance Brew length of 40HL, FVs of 40 and 80HL. Now for every vertical meter of height water will exert 10KPA of static pressure(the gravity of wort would change this but not dramatically), most of Wayward's FVs are near 4m tall, so any lager they produce has 40kpa of static pressure on the yeast where they are working.
Waywards beers taste fine to me. Now if you then think about the static pressure in the vessels CUB, Lion, or even Coopers are using.....

which is why the bigger breweries recirculate their tanks by pumping bottom to top so that the yeast get an average pressure exposure....

 

[wide eyed and legless]

which is why the bigger breweries recirculate their tanks by pumping bottom to top so that the yeast get an average pressure exposure....

Very true but, going into, 'Under pressure fermentation' also diminishes a yeast forward flavour. It is said yeast derives 30% of flavour to beer, so theoretically if we are going to apply a back pressure of say 20 psi to eliminate the esters which yeast add to flavour a beer or lager, does that mean we can use any yeast to ferment our beer/lager?

 

[Coldspace]

Very true but, going into, 'Under pressure fermentation' also diminishes a yeast forward flavour. It is said yeast derives 30% of flavour to beer, so theoretically if we are going to apply a back pressure of say 20 psi to eliminate the esters which yeast add to flavour a beer or lager, does that mean we can use any yeast to ferment our beer/lager?

Interesting , maybe if chasing really clean lager then using diff lager type yeasts might be similar

Might have to try a side by side test with my kegmenters using same receipe but total diff yeasts one day when I get time

 

[droid]

would FUP create a warmer ferment? with little release/escape and all that activity....

 

[Danscraftbeer]

would FUP create a warmer ferment? with little release/escape and all that activity....

I wondered that too. In a 50l kegmenter (still small scale) but I wondered about the temp control. The fridge may be reading 18c but what about in the middle of the brew? So I fitted a thermowell midway so the sensor is literally reading inside the brew temp.

 

[malt junkie]

DCB thinking down this same path have 2 thermowels from beerbelly I plan to have welded in.
Lately have been pushing the boundaries a little with a few ambient (yes the last few days included) ferments @ 15psi. I know at one point it was 38 in there.

One of the beers was the swap brew dropped on a full cake of US05, cube had left over golden syrup and cube hopped with 30gm of simcoe. Tasted this today at lunch after 30 hrs of CC, now I haven't checked FG as yet but it was quite dry and not really enough malt to support the current apparent bitterness. That isn't to say this won't smooth out. I want to leave this for a while and have some others taste, currently I'm not picking hot alcohols or heavy ester flavours.

The second brew was 24hrs behind the swap brew, plain simple: Wey pale 98% Abbey 2% cascade 30,10 and 0 on San Diego super yeast. Being as this is so simple it should show some faults if they're there

I certainly wouldn't recommend pushing this hard; timing Spunding close off was a bit of a challenge and both ferments finished in under 72hrs.

Will report back with more results over the coming weeks.

MJ

 

[Danscraftbeer]

Keep us informed please. 38! woah. It would be nice if pressure ferment can suppress negative flavours like hot alc too. My temp control fridge is making some pretty freakin weird noises here and there I'm worried its gonna kick the bucket...

 

[wide eyed and legless]

would FUP create a warmer ferment? with little release/escape and all that activity....

If you have a wort of 1.045 and an actual attenuation of 65% you will have 'X' amount of KJ to convert, being under pressure wouldn't change that, so the energy factor would be the same. But if you mean what happens to the heat generated, if it can't vent then the only escape would be through the fermenter walls so I would imagine it would be a warmer ferment.

 

[wynnum1]

If you have a wort of 1.045 and an actual attenuation of 65% you will have 'X' amount of KJ to convert, being under pressure wouldn't change that, so the energy factor would be the same. But if you mean what happens to the heat generated, if it can't vent then the only escape would be through the fermenter walls so I would imagine it would be a warmer ferment.

Metal fermenter would be better to transfer heat if you put in a keg with a good amount of head space how quickly would the pressure go up and how high and if not vented would it stop fermentation.

 

[wide eyed and legless]

Metal fermenter would be better to transfer heat if you put in a keg with a good amount of head space how quickly would the pressure go up and how high and if not vented would it stop fermentation.

The speed of the pressure going up will depend on the lag time as the yeast adjusts and gets to work, it isn't the actual pressure that stops the yeast working, it is the dissolved CO2 which slows down the fermentation.

 

[wynnum1]

So at higher temperature higher pressure less dissolved CO2.

 

[Hpal]

I am currently pressure fermenting a lager, it's at about 20psi and 10 degrees, I pitched a starter of yeast from another batch and oxygenated the wort. That was 6 days ago and it's gone from 1.045 to 1.016 in that time and tastes clean as and is carbed. Pressure ferments rock.

Just kegged this lager today, 3 weeks total but could easily do a lager now in 2 - 2.5 weeks. A combiniation of oxygenated wort and pressure fermenting has halved the time. Couple that with stainless fermenter, carbonated beer at the end of ferment and closed transfers to a purged keg and you're onto a winner.

 

[Goose]

Just my 2c of experience. I tried fermenting my lagers under pressure but in all honesty could not notice any difference in the end result. So I went back to atmospheric fermentation.

Dr WEAL, I do apologize I havnt read all 292 posts but you seem to be onto something here, can you summarise your hypothesis please.

If I speed read, do you reckon we should not ferment under pressure, at least until the end, coz you will suppress the desired flavour characteristics of the yeast in which case the only benefit is "free" carbonation ?

 

[malt junkie]

Depends on your desired ester profile. Both high temp ferments, still had ester flavours(my previous post), so in essence you need to balance pressure and temperature to achieve desired outcome. We know pressure suppresses esters, we know heat pushes esters. Much play to be had.

 

[wide eyed and legless]

Just my 2c of experience. I tried fermenting my lagers under pressure but in all honesty could not notice any difference in the end result. So I went back to atmospheric fermentation.

Dr WEAL, I do apologize I havnt read all 292 posts but you seem to be onto something here, can you summarise your hypothesis please.

If I speed read, do you reckon we should not ferment under pressure, at least until the end, coz you will suppress the desired flavour characteristics of the yeast in which case the only benefit is "free" carbonation ?

It depends on what you are trying to achieve, as MJ says the balance between higher temperature and pressure needs to be balanced to keep some esters, but according to those with more scientific knowledge this can only be achieved with lager yeast strains. Ale yeast strains will lead to increased VDK's, for me there is only one way to achieve a perfect pilsner and that is an open fermentation, much like is done in Bavaria and Czechoslovakia. Although reading the Low dissolved oxygen thread and reading more about it on line you can still achieve a good pilsner under a closed system fermentation, by capping the fermentation when there is only 1 or 2 degrees plato left to go. I am going to ferment a AIPA under pressure because the hops are the dominant flavour not the yeast, but it isn't my favourite drink. I like this system because it does give free CO2 and you can naturally carb and more important from my point of view transfer to another vessel without the concern of oxidization, I will be finishing my first brew tonight which was about 23 litres which I have drank straight from the secondary cube over 2 weeks. Still fresh, alive and clear.